In the fiber optical telecommunication systems, it is sometimes advantageous to moderate or attenuate the signal transmitted over the optical fiber. Some form of attenuation medium, such as a mirror or a filter, may be placed in the path of the signal to provide this desired attenuation effect. This attenuation medium may be housed within a structure which is inserted between and mates with a connector at an end of a fiber optic cable and an adapter which mates with and aligns connectors from two optical fiber cables.
In-line optical devices providing different levels of attenuation may be available for insertion within the optical transmission to permit the level of attenuation to match the requirements of the particular devices connected by the cables.
When installing a fiber optic in-line device, it is desirable to ensure that no contaminants such as moisture or dust are present on the polished ferrule end faces within the device. Such contaminants may alter the power of the signal transmitted through the device and change the level of attenuation or other signal alteration provided by the device. In many of the known formats (for example, SC and FC) of mating adapter and connector designs for optical fiber cables, one of the ferrule end faces may be difficult to access directly to clean. Improvements to the structure of in-line devices are desirable to improve access to the ferrule end faces within the device for inspection and cleaning.